From a7923fa19f81ea145f3ce97123567970e88d9df3 Mon Sep 17 00:00:00 2001
From: Alan Alpert <alan.alpert@nokia.com>
Date: Tue, 30 Aug 2011 19:25:11 +1000
Subject: [PATCH] Add more proportionality modes to PointAttractor

Inverse proportionality is now properly named, direct proportionality
is added, and constant as well (in case they all just draw towards a
point).

Change-Id: I6187c0df908fdf20e2bb0b0a1007ebcc38dd3ac2
Reviewed-on: http://codereview.qt.nokia.com/3868
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Martin Jones <martin.jones@nokia.com>
---
 .../declarative/particles/asteroid/blackhole.qml   |    2 +-
 .../particles/spaceexplorer/spaceexplorer.qml      |    6 ++--
 src/declarative/particles/qsgpointattractor.cpp    |   21 ++++++++++++++-----
 src/declarative/particles/qsgpointattractor_p.h    |    5 +++-
 4 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/examples/declarative/particles/asteroid/blackhole.qml b/examples/declarative/particles/asteroid/blackhole.qml
index 4a7ce02..441f4c3 100644
--- a/examples/declarative/particles/asteroid/blackhole.qml
+++ b/examples/declarative/particles/asteroid/blackhole.qml
@@ -149,7 +149,7 @@ Rectangle{
         id: gs; x: root.width/2; y: root.height/2; strength: 4000000;
         system: particles
         physics: PointAttractor.Acceleration
-        proportionalToDistance: PointAttractor.Quadratic
+        proportionalToDistance: PointAttractor.InverseQuadratic
     }
     Kill{
         system: particles
diff --git a/examples/declarative/particles/spaceexplorer/spaceexplorer.qml b/examples/declarative/particles/spaceexplorer/spaceexplorer.qml
index 1bb3cda..727d711 100644
--- a/examples/declarative/particles/spaceexplorer/spaceexplorer.qml
+++ b/examples/declarative/particles/spaceexplorer/spaceexplorer.qml
@@ -276,7 +276,7 @@ Rectangle{
     }
     PointAttractor{
         id: gs1; x: vorteX; y: vorteY; strength: 800000;
-        proportionalToDistance: PointAttractor.Quadratic;
+        proportionalToDistance: PointAttractor.InverseQuadratic;
         system: foreground
     }
     Kill{
@@ -289,7 +289,7 @@ Rectangle{
 
     PointAttractor{
         id: gs2; x: vorteX2; y: vorteY2; strength: 800000;
-        proportionalToDistance: PointAttractor.Quadratic;
+        proportionalToDistance: PointAttractor.InverseQuadratic;
         system: foreground
     }
     Kill{
@@ -302,7 +302,7 @@ Rectangle{
 
     PointAttractor{
         id: gs3; x: vorteX3; y: vorteY3; strength: 800000;
-        proportionalToDistance: PointAttractor.Quadratic;
+        proportionalToDistance: PointAttractor.InverseQuadratic;
         system: foreground
     }
     Kill{
diff --git a/src/declarative/particles/qsgpointattractor.cpp b/src/declarative/particles/qsgpointattractor.cpp
index 55b6cb6..21eaeaa 100644
--- a/src/declarative/particles/qsgpointattractor.cpp
+++ b/src/declarative/particles/qsgpointattractor.cpp
@@ -65,19 +65,28 @@ bool QSGPointAttractorAffector::affectParticle(QSGParticleData *d, qreal dt)
 {
     if (m_strength == 0.0)
         return false;
-    qreal dx = m_y - d->curX();
-    qreal dy = m_x - d->curY();
+    qreal dx = m_x - d->curX();
+    qreal dy = m_y - d->curY();
     qreal r = sqrt((dx*dx) + (dy*dy));
     qreal theta = atan2(dy,dx);
     qreal ds = 0;
     switch (m_proportionalToDistance){
+    case InverseQuadratic:
+        ds = (m_strength / qMax<qreal>(1.,r*r));
+        break;
+    case InverseLinear:
+        ds = (m_strength / qMax<qreal>(1.,r));
+        break;
     case Quadratic:
-        ds = (m_strength / qMax<qreal>(1.,r*r)) * dt;
+        ds = (m_strength * qMax<qreal>(1.,r*r));
         break;
-    case Linear://also default
-    default:
-        ds = (m_strength / qMax<qreal>(1.,r)) * dt;
+    case Linear:
+        ds = (m_strength * qMax<qreal>(1.,r));
+        break;
+    default: //also Constant
+        ds = m_strength;
     }
+    ds *= dt;
     dx = ds * cos(theta);
     dy = ds * sin(theta);
     qreal vx,vy;
diff --git a/src/declarative/particles/qsgpointattractor_p.h b/src/declarative/particles/qsgpointattractor_p.h
index 9571648..298965a 100644
--- a/src/declarative/particles/qsgpointattractor_p.h
+++ b/src/declarative/particles/qsgpointattractor_p.h
@@ -64,8 +64,11 @@ class QSGPointAttractorAffector : public QSGParticleAffector
 
 public:
     enum Proportion{
+        Constant,
         Linear,
-        Quadratic
+        Quadratic,
+        InverseLinear,
+        InverseQuadratic
     };
 
     enum PhysicsAffects {
-- 
1.7.2.5